Hi,Henrik Firstly,thank you for your resolution for my former question about the definition of the material in the injection. Recently,i have got another issue to simulate the concentration polarization phenomenon in the process of membrane filtration involving the separation of solid particles from liquid. I have learned that the filtrating media can be defined as a porous zone boundary in some literatures,however,I didn't get a proper result about the particles concentration distribution near the membrane,which practically has a trendency of condensing in this area. So I wonder if fluent can simulate this problem with a proper accurancy. For the specification in my simulation, the mixtured model is used and respective viscous resistances fot each materials(water and the particles).